Demandas del recurso hídrico

by David S. Alberts, Daniel S. Papp, and W. Thomas Kemp III

Spurred on by the Cold War, the United States during the 1950s and 1960s made massive investments in its scientific and technological infrastructures, particularly those segments related to national defense. Many of these investments, as discussed in Chapter 1, were a driving force behind the enablers of the Information Age: semiconductors, computers, and satellites, some of the primary technologies of the second modern information revolution.

By the late 1980s, the dawn of yet another information revolution had emerged, this time spurred by further advances in and wider dissemination of semiconductors, computers, fiber optics, networking, and other information and communication technologies. While defense spending played a significant role in bringing about this new revolution, private companies and individual entrepreneurs were also a driving force behind many of the emerging new technologies. Many analysts predicted that the effects of this new revolution would dwarf those that had come before. Indeed, it was at this point in history when many analysts began to describe the rapidly approaching 21st century as "the Information Age."1

Subsequent chapters in this book will explore various dimensions of the Information Age. In this chapter, our task is different. Here, we provide a non-technical overview of some of the technologies that have the greatest potential to further expand humankind’s ability to create knowledge and to communicate, and ponder what effects they might have.

The Technologies of the Information Revolution

Many technologies are part of the contemporary information revolution, but eight stand out: (1) advanced semiconductors; (2) advanced computers; (3) fiber optics; (4) cellular technology; (5) satellite technology; (6) advanced networking; (7) improved human- computer interaction; and (8) digital transmission and digital compression. Each will be discussed separately, although in practice the capabilities of several are often combined. Advanced Semiconductors. Semiconductors are arguably the technology that has contributed the most to our current ability to store, process, and communicate information. Indeed, without the advances in semiconductor technology that have taken place over the past 30 years,2 information and communication technologies may have required hundreds of years to advance to their present levels rather than hundreds of weeks. As Chapter 2 showed, advances in communications and information storage and processing capabilities were slow in evolving for most of recorded history. However, with the invention of the semiconductor, the rate of advance in a host of computing capabilities (including expanded memory, faster speed, improved reliability, and overall performance) increased dramatically, often approaching exponential growth.

Semiconductors are made by implanting electronic switches onto silicon wafers. First, a large circular silicon wafer is made. This wafer is then divided into as many squares as

possible; the larger the circular wafer and the more squares that can be cut from the wafer, the better. Small electronic switches are then assembled on the cut square wafers. The final product is a semiconductor.

Semiconductor technology has improved dramatically since the mid-1970s. In 1978, a computer memory chip held approximately 10,000 bits of information; by 1993, each chip could hold roughly 10 million bits of information. Throughout this decade and a half, the amount of computational memory per computer chip increased by a factor of 4 every 3 years.3 This is the equivalent of investing one dollar and having it grow to over 500 dollars in 15 years. These advances were achieved by learning how to more densely populate each silicon wafer and by improving the switches.

Manufacturers also learned how to increase the size of each wafer, allowing still more switches to be placed on each. For example, in 1980, an advanced microprocessor contained perhaps 10,000 transistors; by 1994, this number grew to approximately 100 million transistors, a 10 thousand fold increase. Between 1966 and 1989, semiconductors dramatically increased in size, from 30 mm to 200 mm, increasing the amount of information that could be stored from 3,200 bits to one billion bits. Between 1989 and 1996, the productivity of semiconductors increased over 300,000 times. In the future, 300 mm wafers could contain as many as fifty billion bits, a productivity increase of 16 million.4

Simultaneously, the costs of manufacturing semiconductors declined. In 1970, one bit of information cost roughly one cent to store; by 1990, it cost only one thousandth of a cent to store. This dramatic reduction in storage cost reduced the cost of manufacturing semiconductors, and is projected to continue.5

There is, however, a cloud on the horizon for semiconductors. Advances in semiconductor technology have required finding ways to put additional and/or better designed switches on silicon wafers and to increase the size of the wafer. Recently, however, some manufacturers have concluded that the semiconductor is nearing the physical limits of size and design. Many believe that to continue to improve semiconductor technology, a new manufacturing process must be developed.6

There may be ways to do this. Presently, the creation of the silicon wafer uses two materials. A new manufacturing technology for semiconductors might craft wafers from one material instead of two, thus decreasing the thickness of semiconductors and allowing them to be used more flexibly. Manufacturers are also experimenting with new electronic switches for semiconductors as well as bio-switches and other forms of switches that would increase a semiconductor’s performance without requiring additional wafer space.

If semiconductor technology is to continue to improve, new advances in electronic switching and new technologies for semiconductor manufacturing will be needed. Most experts believe that this will occur.7 If they are right, advanced semiconductors will continue to be a driving force behind the third modern information revolution.

Advanced Computers. Computers are central to all facets of automated information creation, dissemination, and utilization. Since the creation of the world’s first computer, computer capabilities have improved immensely. Enabled by improved microchips, today’s computers are much faster, have much larger capacities, and are much more reliable than those that were used as recently as 2 years ago. Within the information technology community, there is unanimity that computing capabilities will continue to expand. Many experts believe that early in the twenty-first century, high- volume microprocessors will have cracked the so-called "bips barrier" and will be able to execute over one billion operations per second.8 Beyond this, the U.S. Government’s High Performance Computing and Communicating Program expects to create supercomputers with the ability to compute one trillion mathematical operations per second.9

Computers and related technologies are the backbone of the third modern information revolution. Beginning in the early 1970s, the perfection of very large-scale integrated circuits permitted hundreds of thousands of components to be placed on one chip. This led to the development of fourth generation computers,10 which were followed in the late 1970s and 1980s by fifth generation computers such as the Cray super-computer which used multiple processing units to process data simultaneously in a parallel manner. We are fast approaching the time when desktop work stations exceed the computational power of early fifth generation computers. And sixth generation computers that are based on artificial intelligence are on the horizon.

As computer performance improved during the 1980s and 1990s, computer technology doubled its price performance ratio roughly every 18 months. This meant that every year and a half, computers doubled their performance capabilities without increasing their price. There is every expectation that such price performance improvement will continue into at least the near-term future. This raises the possibility that as computer performance improves and costs decline, "ubiquitous computing" will become a reality, that is, computers will recede into the background of consciousness much the way electric motors did because they will be everywhere. Nevertheless, computers will still be there. The transformation of the communications industry occurred when older switching technologies were replaced by digital switches. Hence, computers are now responsible for the global transmission and receipt of voice, video, and digital data; thus, given the volume of global information and communications flows, it is only computerized switching that allows coordination of the world’s information and communications flows in a practical and time-effective manner. Computerized switching has contributed to the creation of a global switching network utilizing cables, microwaves, and satellites so that users of most of the world’s estimated 700 million telephones can talk to each other via standard voice communication or via facsimile machines. Nearly all of the world’s telephone services are now controlled using computerized switching. Computers also allow consumers cost-effective optional features such as touch-tone dialing, call waiting, call forwarding, digital voice mail, and conference calling. As important, computers attached to phone lines with modems and other devices can communicate directly and automatically with other computers regardless of location.

What does the future hold for computer technology? Most analysts believe the future will in many ways be like the past, with continued increases in computational power, greater reliability, continued miniaturization, and even lower costs arriving in rapid fire order. Increasingly, portable computers and other personal digital assistants are being used by business and residential consumers as prices decline, ease of use improves, and features become increasingly enhanced. Hardware advances may soon bring us "wearable" computers and "truly personal" computers that will allow more mobility and freedom of movement for users without sacrificing computing ability.11

Thus, computer advances have helped permit messages, data, and information to be transferred globally on virtually a moment’s notice. As computers continue to become smaller and lighter, as computer power requirements are reduced, as power sources become more portable, and as costs over time decline, computers will become truly ubiquitous. If the information technology community is correct in its predictions of continued rapid advances, the implications for humankind’s ability to communicate and relate to one another, the conduct of the business and government affairs, and the structure of the international system are immense.

Fiber Optics. Historically, telegraph, telephone, and cable television services were carried over copper wires and coaxial cables. These are being phased out by a superior technology, fiber optics. Fiber optics, extremely thin glass fibers, carry light pulses similar to Morse code from a sending source to a receiving destination. Fiber optic cables experience lower attenuation and leakage than copper wire, and can carry much more information and data than either copper wire or coaxial cables. For example, copper wire can carry 64,000 bits of information per second, whereas fiber optics can carry over a billion bits of information per second.12

Similarly, coaxial cable can transmit only 2 to 4 audio channels and 60 video channels. This transmission capacity is adequate for basic telephone and cable television services, but not for connecting to the "information superhighway." By comparison, a cable television company using fiber optics can transmit over 500 channels and allow customers to custom design their own cable television packages.

We have witnessed only the beginning of the expansion of bandwidth offered by fiber optics. Some experts predict that eventually the capacity of advanced fiber optic cables will exceed one trillion bits of information per second.13 If this prediction is accurate, humankind’s capacity to transmit information will expand tremendously as fiber optic technology evolves and is adopted more widely.

Cellular Technology. Until recently, most commercially available two-way capable electromagnetic transmitters and receivers that could cover extended distances required sizable equipment, wire or cable, or some combination of the two. In any case, the locations from which one could transmit and receive messages were tied to technology that could be transported only with difficulty.

The advent of modern cellular and related technologies is changing this. The combination of miniaturization, local radio nets, advanced networks, and improved transceivers that

make up cellular and related technologies is rapidly cutting through the knot that tied telephones to wires or cable and that limited the flexibility of telephonic and related communications.

In the United States and other developed countries, cellular and related technologies entered widespread use in the late 1970s and early 1980s. Since then, the growth in cellular technologies use has been phenomenal. For example, in the United States, commercial cellular systems began operating in 1983; by 1991, approximately 7.5 million Americans subscribed to cellular service; and by 1995, the number had grown to 25 million, with cellular coverage available in half the country. Meanwhile, in Japan, fewer than 250,000 people used cellular phones in 1989; by 1994, the number had grown to 2.1 million people; and by 1996, to approximately 11 million people.14

In essence, cellular telephones are mobile radio transmitters and receivers that look and act like traditional telephones, using radio waves to send and receive messages from remote non-wired locations. Users operate cellular telephones in much the same way that traditional telephones are operated. Unlike land-wired telephones, however, cellular telephones rely on cellular radio towers to transmit messages to and from the cellular user. Users of cellular systems are therefore not tied to sending and receiving locations that are connected by wires.

Although commercial cellular systems have been in use only since the late 1970s and early 1980s, cellular telephone technology is not new. Indeed, it has been used since early in the twentieth century. For example, during World War I, Motorola produced mobile telephones for the Allied armies. These mobile telephones for all practical purposes were the first cellular telephones. Radiophones were similarly used in World War II, the Korean War, and the Vietnam War.15

Although the technology used for communications in these conflicts remained basically the same, the size of the radiophone decreased considerably. Whereas a soldier in World War I required a full backpack to send and receive radio communications, a Vietnam-era soldier needed only a large radio telephone. Today, most cellular telephones are smaller than standard line-wired telephones, and many fit into a shirt pocket. All are powerful enough to send and receive messages several miles. Enhanced miniaturization, advances in networking, and improved transmitter performance will inevitably expand the adoption of cellular technology.

Increasingly, cellular telephone users can also send and receive data as more and more computer users employ cellular telephones in conjunction with computer modems. The combination of cellular technology and portable computers allows people to exchange information to and from virtually anywhere in the world in near real time.

Outside the industrialized world, cellular technology is having a notable impact in many developing states. Newly industrialized countries such as South Korea and Taiwan are using cellular technology to augment existing line-wired telecommunications networks, thereby improving their telecommunications infrastructures without expending resources on land-based telephone lines. Developing countries such as India and some Caribbean

states are building new national telecommunications networks using cellular technology instead of traditional land-based line technology.16 For many of these countries, cellular technologies provide better services than land-lines and have lower installation and maintenance costs. Cellular technology has thus helped some developing states construct advanced national telecommunications infrastructures, thereby accelerating economic development.

The most notable recent advance in cellular technology is the personal communication system (PCS). Using cellular technology and employing extremely small cellular radio repeaters to transmit and receive messages, a PCS has several advantages over a traditional cellular system. First, since a PCS cellular repeater is much smaller than traditional cellular radio towers and can fit inside an office or room, it is more flexible than a traditional cellular repeater.17 Second, a PCS also costs less to install and maintain than a traditional cellular system. However, a PCS also has a disadvantage in that it has a more limited range than a traditional cellular system and hence requires many more repeaters to achieve the same coverage.

As cellular systems proliferate, capabilities increase, and costs decline, more and more people will use cellular technology, and use it not for "emergencies" but as their normal means of communications. There is no doubt, then, that cellular technologies are having a sizable impact on the way people interact by eliminating the need to be "connected" by a tether to a house or an office. Cellular technologies have therefore become a central feature of the contemporary information revolution.

Satellite Technology. Satellites have played a major role in global communications since the first true telecommunications satellite, Syncom III, was launched in 1964. The following year, "Early Bird," the world’s first commercial communication satellite, was launched. Although it could carry only 240 voice channels or one television channel, "Early Bird" was the beginning of a massive global communication revolution.18

Since then, the entire world has been linked together via communication satellites. Theoretically, a global satellite communication network could employ as few as three satellites, but in fact many satellites, most in geosynchronous orbit 23,000 miles above the equator, make up the present-day global satellite communication network. Most low- and middle-latitude countries use these geosynchronous orbits, but countries in higher latitudes such as Russia often use satellites in elliptical orbits because they have difficulty receiving signals from satellites over the equator.

Satellite communication has improved immensely during the first several decades of its existence. Whereas "Early Bird" and its immediate successors carried only a few hundred voice channels, today’s satellites carry thousands of channels for telephone, television, and data transmission. Direct broadcast satellites and store-and-forward satellites are the two main types of communication satellites. A direct broadcast satellite acts as a repeater for information, allowing a broadcast site to send information to a satellite and have that information redirected elsewhere in the world. Store-and-forward satellites allow information to be sent to a satellite, have that information stored until a later time, and transmit that information exclusively to authorized recipients. Direct broadcast satellites

are often employed by broadcast and cable television companies, while governments and private business with sensitive data to protect from unauthorized recipients use store-and- forward satellites.

Satellite technology, in conjunction with computers, telephones, digital compression, and other information and communication technologies, has helped build an international communication infrastructure accessible by governments, business, education, and private consumers. Satellite technology provides information—particularly defense- related and weather-related information—previously unavailable to any but major powers and some international corporations. Satellites have made international telephone calls, global electronic mail, intercontinental teleconferencing, and worldwide broadcasts of television events commonplace. Satellite telephone calls, which directly use communication satellites to send and receive messages, have become the norm rather than the exception.

Increased access to instantaneous satellite communications has tied the world more closely together than ever before. As computer advances, digital technologies and digital compression, and cellular technology are increasingly married with satellite